MBI and Mallinckrodt launch assault on patents of ultrasound contrast foes

MBI also forces review of Sonus contrast patents

Turnabout is fair play in the increasingly bitter war over ultrasound contrast agent technology. Three days after suffering a defeat in the regulation of its Optison agent (see story above), Molecular Biosystems and its marketing partner Mallinckrodt went on the offensive, announcing last week that they have filed litigation in U.S. federal court to have the patents of four potential competitors declared invalid.

MBI also opened up a second front last week by petitioning the U.S. Patent Office (PTO) to review patents granted for contrast technology developed by Sonus Pharmaceutical and Nycomed, and the PTO granted MBI's request for two of the Sonus patents. MBI and Sonus exchanged dueling press releases, with San Diego-based MBI claiming the PTO's action was a major victory, while Bothell, WA-based Sonus characterized the ruling as routine.

MBI and Mallinckrodt announced Aug. 1 that they had filed suit in the U.S. District Court for the District of Columbia in Washington, DC, against Sonus Pharmaceuticals, Nycomed, ImaRx Pharmaceutical and its marketing partner Du Pont Merck, and Bracco. All are developing ultrasound contrast agents that would compete with Optison, which is nearing the end of the Food and Drug Administration review process.

In their lawsuit, MBI and Mallinckrodt charge that the patents of their competitors are invalid on a variety of grounds. MBI chairman Kenneth Widder said that all of the companies named in the lawsuit have been issued patents for the same invention, the development of ultrasound contrast agents containing perfluorocarbon gases. MBI believes that knowledge of the use of perfluorocarbon gas in ultrasound contrast agents was covered in prior art long before the patents were issued.

In addition to requesting that the patents of their competitors be declared invalid, the suit also requests a declaration that MBI and Mallinckrodt do not infringe the patents of others, and that these companies should be enjoined from pursuing infringement claims against MBI and Mallinckrodt until the status of their patents has been determined by the court and the patent office.

The lawsuit reserves special treatment for Sonus and its chief executive, Dr. Steven Quay. The complaint alleges that Quay and Sonus have made "false public statements and engaged in other actions intended to damage MBI and Optison." The lawsuit requests punitive damages and attorney's fees as compensation.

The day before it announced the filing of the lawsuit, MBI reported that it had petitioned the patent office for reexamination of U.S. patent no. 5,558,094, which was issued to Sonus on Sept. 24, 1996. MBI said it filed the petition in response to claims by Sonus that its patents cover agents developed by other companies, such as Optison. Sonus said that MBI is also pursuing the reexamination of another of its patents, no. 5,573,751. Those are two of the eight patents Sonus holds for its ultrasound contrast technology.

The Sonus 5,558,094 patent includes 17 claims regarding the use of perfluorocarbon gases, including perfluoropropane, for ultrasound imaging. MBI claims that this technology is not patentable to Sonus, due to numerous prior art references that Sonus declined to disclose in its original patent application. MBI provided few details on the nature of its claim against Nycomed, which is developing the NC100100 contrast agent.

MBI had originally sought to have four of the 17 claims reviewed, but the patent office has decided to reexamine all 17 claims, according to MBI. MBI said the patent office agreed to grant the company's petition after examining prior art references brought to the agency's attention by MBI. MBI said the patent office's order specifically mentioned one such reference, to the use of Freon gas in ultrasound imaging.

The average duration of a patent reexamination is 19 months, and more than 75% of reexamination proceedings result in cancellation or amendment of some or all of the patent claims, according to MBI. Sonus put a different spin on the news, however. The company said it welcomed the reexamination process, which it claimed would give Sonus the chance to strengthen its patent claims. Sonus said that the patent office almost routinely grants a request for reexamination, but more than 90% of patents under review survive reexamination.

Sonus added that it did not believe that the PTO's action would affect the review of its EchoGen contrast agent, which is moving through the FDA process again after a delay related to the dispute between contrast companies over how such agents should be regulated.

The jockeying between MBI and Mallinckrodt and their contrast competition could result in a bruising fight over patents on ultrasound contrast technology that could potentially delay the introduction of products to market. A similar confrontation took place in the MRI industry in the early 1990s as Schering pressed patent claims for its Magnevist agent against Sterling Winthrop (now Nycomed) and Squibb Diagnostics (now Bracco). That dispute was eventually settled before the Sterling and Squibb products reached the market.